In some floor polishers, the driving shaft for the polisher pad has coupling means thereon and the polisher pad is directly secured to the coupling means. However, this is subject to certain disabilities. Firstly a harshness is transmitted by the machine to the operator (due to high frequency vibration) and secondly, there is difficulty in maintaining an even pressure over a wide area of brush or polisher pad.
Considerable improvements have been made by utilising two comparatively rigid discs which are joined together by a slab of comparatively resilient foam material, for example polyurethane foam, and this has been found to have the effect of substantially eliminating transmission of high frequency (harsh) vibrations, and also enabling the floor polishing brush or pad to maintain a relatively large area in contact with a floor even when the machine is tilted through a few degrees, for example, by a partly skilled operator. However, the soft resilience of foam material has given rise to further problems, the foam material being very easily damaged, for example by encountering the cord of the polisher, or the possibility of one of the two discs warping, or the discs not lying parallel to one another, and imparting unstable conditions to a brush. Difficulty has also been encountered with the effectiveness of the glue interfaces between the upper and lower surfaces of the foam and the respective discs. Another problem which has been encountered with the use of soft polystyrene mounting means has been the tendency for "wobble" to occur in a machine. When a polisher is needed for scrubbing, any wetting of the foam causes it to lose some of its resilience and to quickly deteriorate.
A series of experiments have indicated that there is a need to have a degree of resilience so that an operator can tilt a machine through a few degrees without losing area of contact of the polishing brush or pad with the floor surface. On the other hand, it is necessary to have sufficient stiffness to "iron out" wobbles as they tend to develop.